I am planning a flow through muffler installation soon. The Donaldson flow through muffler I am looking at is 4" in and out. Since my stock tail pipe is 4" (about 2" past where the pipe exits the muffler pipe), I will have new 4" muffler to stock 4" tail pipe. Do the 4" band clamps I have seen work well for connecting 4" to 4" and do they seal well? I have not used them before and would like to have everything I need when I do the installation.

 

they seal well enough for exhaust systems dry, but if you want some extra sealing, you can put some permatex or silicone on the sealing surface. the real good part about the band clamps is if you need to take things apart later, they come apart easy [no crimping]

 

I used a combination of butt-joint and slip-joint band clamps on my 4" system. The butt-joints were Walker SS clamps, from Summit. For the slip-joint clamps, I found them at NAPA, made by Torco, part number 733-3224 (that's a NAPA part number).

These things seal up very well. I also used hi-temp silicone around the joints, and have absolutely no leaks. What's really nice about this set-up is that I put my down pipe in with a butt-joint clamp, which means the downpipe can be disconnected and removed without touching the rest of the exhaust system. Try that with the stock system!